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Page 11 of 23 <br />Chemical Control of Russian Knapwecd <br />Appendix 1 <br />[n most circumstances, an he~icide alone will not effectively manage Russian knapweed However, there <br />may be situations where desirable plants within a Russian knapweed infestation may compete effecaively <br />with the weed if it is stressed with a single weed management technique. When integrating chemical and <br />cultural control, avoid using herbicide rates that injure grassea because effective competition will be <br />reduced. <br />Russian knapweed is controlled with Tordon 22K (picloram) at 1 to 2 quarts/A. Tordon may be broadca <br />sprayed up to 1 quart/A or spot sprayed at rates up to 2 quarts/A Tordon plus 2,4-D (1 to 1 5 pints + I <br />quart/r1) also will control Russian knapweed If low rates of Tordon or Tordon plus 2,4-D are used, <br />application for two consecutive years may be necessary to achieve adequate control..Apply Tordon any <br />time the weed is actively growing. <br />For "I'elar (chlorsulfuron), a noncrop herbicide that controls Russian knapweed, application timing is <br />critical. Apply (1 ounceJA) when Russian knapweed is in the bloom to posthloom stage. Earlier <br />applications do not control the weed effectively. Fall is a gcx~d time to apply Telar, but it may injure smooth <br />brome or other brome species. Always add a good agriculnu~al surfactant at 0.25 to 0.5 percent v/v to the <br />spray solution. Escort (metsulfuron) is labeled for pasture and rangeland use. Apply it at U 75 to 1 ounce/A <br />with a good agricultural surfactant. Optimum timing for Escort is similar to Telar <br />;~1echanical Control of Russian knapweed <br />Russian knapweed tends ro form monocultures and usually eliminates other plants. 'T'herefore, sowing <br />desirable plant species is necessary after the weed is controlled. Smooth brome will compete with Russian <br />knapweed. Research shows that streambank wheatgrass, thickspike wheatgrass, crested wheatgrass and <br />Russian wildrye established after Russian knapweed was suppressed with herbicides Sod-forming <br />perennial grasses, like streambank or thickspike wheatgrasses, help prevent reinvasion better than bunch <br />grasses like crested wheatgrass. <br />If the Russian knapweed stand is not too old and grasses are stilt present, stimulating grass growth by <br />irrigation (where possible] should increase grass competition with knapweed and keep the weed under <br />continual stress. <br />Spotted knapweed <br />